关键词: 内生菌, 拮抗, 促生, 纤维素降解

Abstract: Plant endophytic bacteria can enhance not only the ability of host plants to resist biological and abiotic stresses,but also the ability of decomposition and absorption of mineral elements such as phosphorus and potassium,thus it confers to promote plants growth.In this article the antagonistic effect of endophytic strain BN7 isolated from Chrysanthemum morifolium Ramat ‘Boju’ was tested on six plant pathogenic fungi,including Curvularia lunata,Fusarium oxysporum,F. graminearum,F. moniliforme,Colletotrichum lagenarium and Pestalotiopsis theae.And its ability of dissolving phosphorus and potassium,producing indoleacetic acid and scavenging DPPH was tested,too.Strain BN7 was identified based on the morphological characteristics,physiological and biochemical characteristics and 16S rDNA sequence analysis.Results showed that endophytic strain BN7 had the ability to inhibit the six plant pathogens mentioned above with varying degrees.The available phosphorus in organic phosphorus fermentation broth and inorganic phosphorus fermentation broth increased to 108.38 mg/L and 68.71 mg/L,respectively.And the available potassium increased to 32.03 mg/L,IAA reached to 164.39 mg/L.The strain had the highest cellulase activity after incubation for three days.The CMC enzyme activity and FPA activity reached 168.78 and 79.87 U/mL,respectively.The DPPH scaveging rate reached 82.13% by fermentation supernatant of BN7 incubated for seven days.According to the morphological characteristics,physiological and biochemical characteristics and 16S rDNA sequence analysis,strain BN7 was identified as Bacillus megaterium.Therefore,strain BN7 is identified as Bacillus megateriumwith the ability of antagonistic effect on plant pathogenic fungi,disolving phosphorus and potassium,producing IAA,and the ability of cellulose degradation.

Key words: endophytic bacterium, antagonism, growth-promoting, cellulose degradation